The invention relates to a method for positioning webs of film of a packaging device, according to which goods are introduced in a first web of film moving in the advance direction in troughs in this first web of film and then a second web of film is withdrawn from a supply of web against the resistance of a brake and is placed on the first web of film and bound with the same with the advance of the second web of film downstream of the supply of web being detected by a recognition means and set by varying the brake force of the brake in dependence on the signal from the recognition means so that in each case a repeat as a defined area of the second web of film comes to lie on the troughs in the first web of film. In addition, the invention relates to a packaging device for the performance of this method.
A method of this kind or a packaging device of this nature is generally known. Here, the first web of film is provided with the troughs into which the goods to be packed are introduced. Then, the second web of film is placed on this first web of film provided with the goods and welded thereto, either using vacuum technology or with inclusion of air, for example in a sealing station. Subsequently, the individual troughs with the surrounding area of film are separated from each other and in this way individual items of goods packages are produced. This packaging method is frequently used for foodstuffs, but may also be used for other goods. For the inscription of the packaging, generally the second web of film is imprinted, with this frequently taking place completely so that, for example, the packed goods may be protected against UV light. The imprint is divided into repeats according to the packaging length so that one repeat comes to lie over each trough.
For purposes of appearance and to guarantee an airtight welding, the top, second web of film is preferably under tension so that no folds occur during the later packaging. For this, the second web of film is withdrawn from a supply, which may, for example, be formed from a roll, against the restraining force of an adjustable brake. The second web of film, which is under tension, is then placed on the first web of film by means of guides and then welded, whereby adjustment of the brake force may be used to set the position and extension of the flexible web of film. In practice, for example, the imprint should be performed so the desired image only appears after a certain pretension of the second web of film.
The position of the individual repeats is detected by a recognition means, whereby a regulator may be used to set the brake force so that the rate of advance of the second web of film may be matched to that of the first web of film.